Introduce rb_insert_augmented(), which is a version of rb_insert_color()
with an added callback on tree rotations. This can be used for insertion
into an augmented tree: the handcoded search phase must be updated to
maintain the augmented information on insertion, and then the rbtree
coloring/rebalancing algorithms keep it up to date.
rb_insert_color() is now a special case of rb_insert_augmented() with
a do-nothing callback. I used inlining to optimize out the callback,
with the intent that this would generate the same code as previously
for rb_insert_augmented(). This didn't fully work, as my compiler output
is now *smaller* than before for that function. Speed wise, they seem
comparable though.
Signed-off-by: Michel Lespinasse <walken@xxxxxxxxxx>
---
include/linux/rbtree.h | 5 +++++
lib/rbtree.c | 14 +++++++++++++-
lib/rbtree_test.c | 31 +++++++++++++++++++++++--------
3 files changed, 41 insertions(+), 9 deletions(-)
diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h
index bf836a2..1364b81 100644
--- a/include/linux/rbtree.h
+++ b/include/linux/rbtree.h
@@ -61,6 +61,11 @@ struct rb_root {
extern void rb_insert_color(struct rb_node *, struct rb_root *);
extern void rb_erase(struct rb_node *, struct rb_root *);
+typedef void rb_augment_rotate(struct rb_node *old, struct rb_node *new);
+
+extern void rb_insert_augmented(struct rb_node *node, struct rb_root *root,
+ rb_augment_rotate *augment);
+
typedef void (*rb_augment_f)(struct rb_node *node, void *data);
extern void rb_augment_insert(struct rb_node *node,
diff --git a/lib/rbtree.c b/lib/rbtree.c
index 8b111cc..a6ae4c5 100644
--- a/lib/rbtree.c
+++ b/lib/rbtree.c
@@ -88,7 +88,8 @@ __rb_rotate_set_parents(struct rb_node *old, struct rb_node *new,
root->rb_node = new;
}
-void rb_insert_color(struct rb_node *node, struct rb_root *root)
+inline void rb_insert_augmented(struct rb_node *node, struct rb_root *root,
+ rb_augment_rotate *augment)
{
struct rb_node *parent = rb_red_parent(node), *gparent, *tmp;
@@ -152,6 +153,7 @@ void rb_insert_color(struct rb_node *node, struct rb_root *root)
rb_set_parent_color(tmp, parent,
RB_BLACK);
rb_set_parent_color(parent, node, RB_RED);
+ augment(parent, node);
parent = node;
tmp = node->rb_right;
}
@@ -170,6 +172,7 @@ void rb_insert_color(struct rb_node *node, struct rb_root *root)
if (tmp)
rb_set_parent_color(tmp, gparent, RB_BLACK);
__rb_rotate_set_parents(gparent, parent, root, RB_RED);
+ augment(gparent, parent);
break;
} else {
tmp = gparent->rb_left;
@@ -192,6 +195,7 @@ void rb_insert_color(struct rb_node *node, struct rb_root *root)
rb_set_parent_color(tmp, parent,
RB_BLACK);
rb_set_parent_color(parent, node, RB_RED);
+ augment(parent, node);
parent = node;
tmp = node->rb_left;
}
@@ -202,10 +206,18 @@ void rb_insert_color(struct rb_node *node, struct rb_root *root)
if (tmp)
rb_set_parent_color(tmp, gparent, RB_BLACK);
__rb_rotate_set_parents(gparent, parent, root, RB_RED);
+ augment(gparent, parent);
break;
}
}
}
+EXPORT_SYMBOL(rb_insert_augmented);
+
+static inline void dummy(struct rb_node *old, struct rb_node *new) {}
+
+void rb_insert_color(struct rb_node *node, struct rb_root *root) {
+ rb_insert_augmented(node, root, dummy);
+}
EXPORT_SYMBOL(rb_insert_color);
static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
diff --git a/lib/rbtree_test.c b/lib/rbtree_test.c
index 2dfafe4..5ace332 100644
--- a/lib/rbtree_test.c
+++ b/lib/rbtree_test.c
@@ -67,22 +67,37 @@ static void augment_callback(struct rb_node *rb, void *unused)
node->augmented = augment_recompute(node);
}
+static void augment_rotate(struct rb_node *rb_old, struct rb_node *rb_new)
+{
+ struct test_node *old = rb_entry(rb_old, struct test_node, rb);
+ struct test_node *new = rb_entry(rb_new, struct test_node, rb);
+
+ /* Rotation doesn't change subtree's augmented value */
+ new->augmented = old->augmented;
+ old->augmented = augment_recompute(old);
+}
+
static void insert_augmented(struct test_node *node, struct rb_root *root)
{
- struct rb_node **new = &root->rb_node, *parent = NULL;
+ struct rb_node **new = &root->rb_node, *rb_parent = NULL;
u32 key = node->key;
+ u32 val = node->val;
+ struct test_node *parent;
while (*new) {
- parent = *new;
- if (key < rb_entry(parent, struct test_node, rb)->key)
- new = &parent->rb_left;
+ rb_parent = *new;
+ parent = rb_entry(rb_parent, struct test_node, rb);
+ if (parent->augmented < val)
+ parent->augmented = val;
+ if (key < parent->key)
+ new = &parent->rb.rb_left;
else
- new = &parent->rb_right;
+ new = &parent->rb.rb_right;
}
- rb_link_node(&node->rb, parent, new);
- rb_insert_color(&node->rb, root);
- rb_augment_insert(&node->rb, augment_callback, NULL);
+ node->augmented = val;
+ rb_link_node(&node->rb, rb_parent, new);
+ rb_insert_augmented(&node->rb, root, augment_rotate);
}
static void erase_augmented(struct test_node *node, struct rb_root *root)
--
1.7.7.3
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